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Introduction

This is a relatively short introduction to TCL/TK, which is designed to get you started in using TCL/TK. It is not a manual, or a comprehensive book on TK, or a book on programming, but attempts to introduce TCL/TK at a level which will be appropriate for most readers with some previous programming experience. Further information on TCL/TK can be found in the books by Ousterhout [1] and Welch[2]. Some readers may also find that examining the source files (such as the widget demo program) supplied with the distribution, will be helpful. [These are currently at /vol/PACK./tcl-7.3/tkX/3.6a-p2/demos on the Brunel filestore] In addition, there is a newsgroup for exchange of information about TCL

comp.lang.tcl

and there are several Frequently Asked Questions files (FAQs) available by ftp from

ftp://harbor.ecn.purdue.edu/pub/tcl/docs/tcl-faq.part0[1..5].gz

or via hypertext links - link1, link2, link3, link4, link5.

There is also a link to further information via the WWW.

This document also contains a number of small, but perhaps useful, examples, including: a name and address book, a simple file browser and a small text editor.

TCL/TK is a programming system developed by John Ousterhout at the University of California, Berkeley,, which is easy to use, and which has very useful graphical interface facilities. TCL is the basic programming language, while TK is a ToolKit of widgets, which are graphical objects similar to those of other GUI toolkits, such as Xlib, Xview and Motif. Unlike many of the other toolkits, it is not necessary to use C or C++ in order to manipulate the widgets, and useful applications can be built very rapidly once some expertise of the TCL/TK system has been gained.

Some users will naturally wish to use the widgets with C or C++. The TCL/TK system can be configured to work co-operatively with other programming languages such as C or C++, and facilities to support this are described in section 3 of Ousterhout's book.

Many users will wish to use TCL/TK with Unix systems or PC DOS systems. While extensive use of Unix or DOS features may render applications less portable, nevertheless many users will wish to use links to the operating system commands, and this will be very useful for packaging up existing programs in easy to use units.

The TCL language is normally interpreted, so TCL applications will normally not run as fast as equivalent C programs. For a large class of applications this is not a disadvantage, however, since the speed of processing of modern computer systems is more than adequate. Where speed of processing is essential, use can be made of a TCL compiler, or processing can be carried out in a compiled language, such as C or C++, and the user interface written in TCL.

There are versions of TCL for different hardware systems, and for different operating systems, so TCL is to a large extent portable. However, it has already been noted that where TCL programs are used to access operating systems feature, portability will be sacrificed to convenience on the user hardware.